What happens while urban changes of prolonged and complex developments are completed? Formal norms and regulations can produce “temporary” situations that suspend many urban fragments indefinitely. Is it possible to think of that interim time within its own logic, designing projects dedicated to improving that transitional condition? Practices such as Tactical UrbanismUrbanism include a wide range of design actions, allowing an immediate impact on local communities. In Buenos Aires, Argentina, a specific urban regulation dating from 1977 caused a series of odd patchworks due to incomplete street widenings. After the urban code was updated in 2018–2021, the list of streets and avenues to be widened was substantially reduced—though several inconvenient side effects will persist over time. As part of a long-term research, this chapter includes montages and collages featuring case studies of socially driven projects, such as mobile libraries, pocket parks, ephemeral games, communal tables, manufacturing workshops, and murals. The concept of tactical urbanismUrbanism represents a paradigm shift in the field of traditional urbanismUrbanism and architectureArchitecture. In the 50 and 60s, the idea of participatory design began to emerge, empowering local communities. This text explores how architectureArchitecture can be viewed as a community service and how participatory design processes can be more important than the building itself, showcasing examples mainly from Buenos Aires, Argentina, such as the “Monteagudo HousingHousing Complex,” the redevelopmentRedevelopment plan for “Barrio 31 Carlos Mugica,” a77’s “Nomade Cultural Center,” or “Clemente´s Plaza.”